/**
 * @file cfgym/103389/j/main.cpp
 * @brief
 * @see
 * @author Ruiming Guo (guoruiming@stu.scu.edu.cn)
 * @copyright 2022
 * @date 2022/5/15 13:11:29
 **/

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
int main() {
  // High rating and good luck!
  double n;
  scanf("%lf", &n);
  printf("%.16lf", 1 / n);
  return 0;
}
